1. Field of the Invention
The present invention relates to a pressure density equalization apparatus and more particularly to a pressure density equalization apparatus for two rotary electric machines in order that the pressure densities of the cooling gases enclosed in the hermetically sealed vessels each pertaining to the rotary electric machines, respectively, can be equalized.
2. Description of the Prior Art
In a turbine generator as a rotary electric machine it has been common practice to cool it by a hydrogen gas, and the hydrogen gas itself is adapted to be cooled by drying through suitable means.
The present invention principally concerns the equalization between the pressure densities of the gases, e.g. the hydrogen contained in two hermetic vessels within which rotary electric machines are mounted for rotation, and which are each provided with gas driers for the cooling gases.
FIG. 1 of the attached drawings schematically indicates a conventional pressure density equalizing apparatus as used for cooling two turbine generators using hydrogen gas as a cooling medium.
Enclosed within first and second vessels 1a and 1b are e.g. hydrogen gases for cooling first and second turbine, respectively generators (not shown). A first and a second blower 2a and 2b are shown schematically connected to rotary shafts 3a and 3b of the 1st and 2nd turbine generators, respectively, and are disposed within the 1st and 2nd vessels 1a and 1b, respectively. The 1st and 2nd gas driers 4a and 4b dry the hydrogen gas coolant enclosed within the 1st and 2nd vessels 1a and 1b, respectively, and are connected to the 1st and 2nd vessels 1a and 1b through a 1st and a 2nd high pressure pipe 5a and 5b as well as a 1st and a 2nd low pressure pipe 6a and 6b, respectively. A communicating tube 7 connects 1st and 2nd vessels 1a and 1b for the purpose of equalizing the pressures of the cooling hydrogen gas coolant within the 1st and 2nd vessels 1a and 1b.
The operation of the apparatus described above and shown in FIG. 1 is as follows:
Upon rotation of rotary shafts 3a and 3b, 1st and 2nd blowers 2a and 2b rotate. Owing to the wind flow caused by rotating blowers 2a and 2b, the cooling hydrogen gases enclosed within the 1st and 2nd vessels 1a and 1b flow into the 1st and 2nd gas driers 4a and 4b, respectively, through the respective 1st and 2nd high pressure pipes 5a and 5b, and after drying, the gases return to 1st and 2nd vessels 1a and 1b, respectively, through their respective low pressure pipes 6a and 6b. In this case, the densities of the cooling hydrogen gases within the 1st and 2nd vessels 1a and 1b are equalized by communication tube 7.
However, in the conventional apparatus explained above, since the air volumes penetrating from the outside into 1st and 2nd vessels 1a and 1b differ between two vessels 1a and 1b there arises a very slight difference in the densities of the hydrogen gas coolant between vessels 1a and 1b. Owing to this difference in the densities there arises a difference in the wind pressures induced by the rotations of the 1st and 2nd blowers 2a and 2b, so that there occurs also a difference in the drying of the hydrogen gas coolant within the 1st and 2nd driers 4a and 4b. This difference increases in an accelerating manner as the cooling hydrogen gases circulate so that the pressures within vessels 1a and 1b do not become equal in spite of the provision of communication tube 7. Further, in one of the turbine generators in which the cooling hydrogen gas density is higher than the other turbine generator the cooling effect is decreased, and the mechanical loss is also increased. Therefore, as the density of the cooling hydrogen gas increases within one of the turbine generators this turbine generator must have the hydrogen gas therein replaced.
Thus, it will be apparent that a study of the conventional pressure density equalizing apparatus reveals various defects.